Typical asphalts are essentially mixtures of bitumen, as binder, with aggregate, in particular filler, sand and stones. There are many different types of asphalts available and their characteristics can vary quite significantly. The design of asphalts for roofing applications is a complex process of selecting and proportioning materials to obtain the desired properties in the finished construction while minimize undesirable characteristics. Asphalt compositions for roofing typically may not include aggregates.
In evaluating and adjusting mix designs, the various components of the asphalt composition are balanced between the stability and durability requirements for the intended use. The final goal of mix design is to achieve a balance among all of the desired properties. Binders and various polymers have been investigated for reaching similar goals, and other modifications have been studied.
Besides performance and environmental issues associated with many types of asphalt modifiers, many of the polymers that are used to modify asphalt compositions are expensive and can be difficult to obtain in remote areas of the world. A need exists for a filler than can be used in asphalt compositions. Historically, limestone powder, limestone dust and cement dust have been used as filler.
The Heavy Oil Fly Ash (OFA) is a black powder waste material that results from burning fuel and cracked fuel oil for power generation and water desalination. The current practice for the disposal of the oil ash is through burying it in special lined and sealed pits which is very costly and requires large area to be reserved as dumping site. Heavy oil fly ash is collected in the electrostatic precipitators (ESP) which are installed on boilers burning residual oil, for air pollution control. Alternative means of disposal or disposition of heavy oil fly ash is also desired, as it will reduce the environmental impact of such processes and reduce costs associated with disposal.